Confronted with some of life’s upsetting experiences – marriage breakdown, unemployment, bereavement, failure of any kind – many people become depressed. But others don’t. Why is this?

A person who goes through experiences like that and does not get depressed has a measure of what in the psychiatric trade is known as “resilience”. According to Manchester University psychologist Dr Rebecca Elliott, we are all situated somewhere on a slidling scale.

“At one end you have people who are very vulnerable. In the face of quite low stress, or none at all, they’ll develop a mental health problem,” she says. “At the other end, you have people who life has dealt a quite appalling hand with all sorts of stressful experiences, and yet they remain positive and optimistic.” Most of us, she thinks, are somewhere in the middle.

But what is this resilience? Is it something we inherit or do we learn it? Can it be traced in the chemistry of the brain? Or in its wiring, or its electrical activity? And if we lack it, can we acquire it? The answer, regrettably, to all those questions is much the same. We don’t really know. But we’d like to, and we need to.

What we refer to as resilience is the outcome of a complex and continuing set of interactions between our genes, our body chemistry, the wiring of our brains, and our life experiences. But whatever the means, finding some way to boost resilience is an ambition well worth pursuing.